Brachyura, Linnaeus, 1758

Starzyk, N, 2016, Three new species of the genus Tanidromites (Decapoda: Brachyura: Tanidromitidae) from the Late Jurassic (Oxfordian) of Poland, Palaeontologia Electronica 19 (3), pp. 1-14 : 4-5

Infraorder BRACHYURA Linnaeus, 1758 Section DROMIACEA de Haan, 1833

Superfamily HOMOLODROMIOIDEA Alcock, 1900

Family TANIDROMITIDAE Schweitzer and Feldmann, 2008

Genus TANIDROMITES Schweitzer and Feldmann, 2008

1835 Prosopon von Meyer , p. 329 (pars).

1824 Pithonoton von Meyer , p. 71 (pars).

1861 Coelopus Étallon , p. 148 (pars).

Diagnosis (from Schweitzer and Feldmann, 2008, emended). Carapace longer than wide; width of hepatic region is 0.60-0.75 of length, moderately to strongly vaulted transversely and longitudinally. Lateral margins parallel or converging slightly posteriorly; lateral flanks very strongly developed. Regions are distinct, usually smooth; epigastric region inflated. Protogastric and hepatic regions not differentiated. Rostrum is downturned, triangle shaped, with blunt end or with pseudorostral spines, with raised borders, divided by an axial groove. Augenrest is various, from flat to concave with differentiated shape of margins. Weak, short lateral ridge extending posteriorly from the augenrest. Angle between long axes of the augenrest and the body is 35-65°. Cervical and branchio-cardiac grooves are deep (emendations in italics).

Type species. Prosopon insigne von Meyer, 1860 , by original designation.

Other species included. T. alexandrae Starzyk, 2015 ; T. etalloni (Collins in Collins and Wierzbowski, 1985), as Coelopus ; T. lithuanicus Schweigert and Koppka, 2011 ; T. maerteni Fraaije et al., 2013 ; T. montreuilense Crônier and Boursicot, 2009 ; T. pustulosa ( von Meyer, 1840), as Pithonoton ; T. raboeufi Robin et al., 2015 ; T. richardsoni ( Woodward, 1907), as Prosopon ; T. scheffnerae Schweigert and Koppka, 2011 ; T. sculpta (Quenstedt, 1857), as Prosopon ; T. longinosa n. sp., T. wysokaensis n. sp., T. schweitzerae n. sp.

Age. The genus is known from the lower upper Bajocian to Tithonian ( Fraaije et al., 2013).

Key to species of the genus Tanidromites . All the species known before and those described herein are included in the key. The nine species redescribed or described by me ( T. alexandrae , T. etalloni, T. insignis, T. lithuanicus , T. sculpta, T. scheffnerae , T. longinosa n. sp., T. schweitzerae n. sp., T. wysokaensis n. sp.) are presented in Figure 2 . Other species characters are known from the literature ( T. maerteni – Fraaije et al., 2013, T. montreuilense – Crônier and Boursicot, 2009, T. pustulosa – Schweitzer and Feldmann, 2010, T. raboeufi - Robin et al., 2015, T. richardsoni – Schweitzer and Feldmann, 2008; Schweigert and Koppka, 2011).

1a. Outer orbital spine and anterior groove present.................................2

1b. Outer orbital spine and anterior groove absent..................................8

2a. Hepatic tubercles absent [hepatic pits distinct; augenrest short, rounded; regions of carapace strongly vaulted]................ T. lithuanicus

2b. Hepatic tubercles present...................3

3a. Hepatic pits absent [carapace slightly narrowing posteriorly; broad rostrum]....... 7 T. richardsoni

3b. Hepatic pits present.......................4

4a. Augenrest flat, without elevated upper and suborbital margins........................5

4b. Augenrest protected by upper and suborbital margins [hepatic pits and tubercles weakly developed].................... T. alexandrae

5a. Lateral borders of carapace parallel or narrowing posteriorly...............................6

5b. Lateral borders of carapace narrowing anteriorly................... T. montreuilense

6a. Spine on the lateral border, in front of branchio-cardiac groove present [cervical groove arched backward on both sides of cervical pits]..................... T. maerteni

6b. Spine on the lateral border in front of branchio-cardiac groove absent.....................7

7a. Distance from rostrum to end of augenrest is the smallest among all species of the genus, outer orbital spines small, blunt; carapace slightly narrowing posteriorly]............... T. sculpta

7b. Distance from rostrum to end of augenrest is long; augenrest short, sharply ended....... T. insignis

8a. Hepatic tubercles absent...................9

8b. Hepatic tubercles present [outer orbital spines and hepatic pits absent; augenrest very short, rounded; rostrum sharply ended]................ T. scheffnerae

9a. Augenrest longer than wide, protected by suborbital margin [hepatic pits absent, rostrum short, rounded].......... T. schweitzerae n. sp.

9b. Augenrest as long as wide or wider than long, flattened...............................10

10a. Rostrum short (R/RtC≤0.3).................11

10b. Rostrum long (R/RtC>0.3) [regions of carapace flattened; posterior part of augenrest weakly distinguished; four short spines on upper orbital margin; hepatic pits absent]................... T. longinosa n. sp.

11a. Rostrum rounded........................12

PALAEO- ELECTRONICA.ORG

11b. Rostrum sharply ended [augenrest narrowing posteriorly, sharply ended; triangular mesogastric region; anterior groove, outer orbital spine, hepatic pits absent]....................... T. etalloni 11c. Rostrum with pseudorostral nodes [carapace convex; hepatic pits absent; augenrest rounded]......................... T. raboeufi 12a. Carapace long and strongly vaulted [hepatic pits absent]................ T. wysokaensis n. sp. 12b. Carapace short [hepatic pits absent]........................ T. pustulosa

It is noteworthy that the abundance of a various newly described structures on the carapace allows determining the specimens even if they are only fragmentarily preserved.

Figures

FIGURE 2. Anterior part of the carapace and the augenrest in Tanidromites spp. The area of augenrest is shaded.